Various methods for evaluating performance of an optical fiber have been discussed. For example, coupled multi-core optical fibers have been evaluated in Roland Ryf, et al. “Coherent 1200-km 6×6 MIMO Mode-Multiplexed Transmission over 3-Core Microstructured Fiber,” ECOC Postdeadline papers Th.13.C.1 (2011) and Taiji Sakamoto et al. “Fiber Twisting- and Bending-Induced Adiabatic/Nonadiabatic Super-Mode Transition in Coupled Multicore Fiber,” J. Lightw. Technol., 34(4), 1228-1237 (2016).